Tinting process and product thereof.



man at Fm.

JOHN I. CRABT'REE, OF ROCHESTER, NEW YORK, ASSIGNOR TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

TINTINQ PROCESS AND PRODUCT THEREOF.

No Drawing.

parent bodies by means of colored inorganic salts in finely divided or colloidal condition. It also relates to the product of this process. More particularly it relates to the coloring or tinting of colloids such as gelatin, cellulose and its derivatives, albumen, soluble starch, dextrin, water soluble gums, etc.

For example, my process maybe used for tinting the gelatin layer of motion picture p'ositive films or lantern slides, or for related light-modifying. uses. a

The objects of my invention are to provide a cheae1 process of tinting by inorganic means in W lch the color and depth of the tint will be under very exact control; in which a satisfactory tint may be easily and precisely duplicated; in which the wearing qualities of the product will notbe impaired;

'in which the colors will be stable to light,

and in which the colors incertain instances may be removed chemically if desirable. Other objects are to provide a product in which an inorganic tint is of the color and depth desired, which has unimpaired wear' ing qualities, in which the colors are stable to light and in which the colors may in 'certain instances be removed by chemical means or solvents. Further objects will hereinafter appear.

Inasmuch as present conditions in the dyestufi' industry render it difiicult to obtain the necessary organic dyes for staining motion picture positive films to give special color effects, a cheaper way of obtaining the desired result has been sou ht after in the motion picture industry. y process is well adapted to staining such film. Therefore, I have chosen as examples of my invention, three typical applications of it to the motion picture art. It should be understood, however, that it is not limited thereto except as indicated in the claims. I

Motion picture positive film ordinarily comprises a flexible transparent base on which is a layer of transparent gelatin, and

in the gelatin are'the small particles of sil- Specification of Letters Patent. Patented Sept. 17, 1918*.

Application filed January 25, 1917. Serial No; 144,556.

ver constituting the image, this silver image I hitherto by using expensive organic dye stufis as the agents for staining the gelatin. The examples of my method, which will be given, relate chiefly to a modification of this second method in which inorganic coloring matter is substituted for the moreexpensive organic dyes. It is to be understood that even if a certain extent of toning or alteration in the color of the silver image should incidentally take place in my method, it is usually indeteotable in the preferred form of my invention, and inany event is not material. I e,

Broadly stated I precipitate colored metallic salts within the colloidal layer. To this end I use two solutions, one containing a soluble salt of the metal which is to enter into the precipitate and another containing a soluble salt which furnishes the acid radical which is toenter into the precipitate.

The metals which furnish the best com pounds appear to be iron, uranium, lead, copper, bismuth, cadmium, tin, tungsten, molybdenum, silver, mercury, cobalt, "or nickel. The best acid radicals appear. to be those which form ferrocynanids 0r sulfids minutes in 'a 1% solution of ferric-alum,

then rinsed and then immersed in a 1% solution of potassium ferrocyanid until the lOO desired tint is obtained. The film is then I well washed for 10 to 15 minutes. The com trol of the tint is obtained by regulating several factors. A blue tint due to colloidal ferric ferrocyanid is obtained.

The depth of the tint obtained increases with increasing concentration of the ferricalum, and the strength of the solution which may be employed, of course, can be varied to suitthe operators needs. I have found,

' siderable efi'ect, a shorter the rinsing may sometimes with.

however, that a 1% solution is sufiiciently strong in practice and is usually preferable to stronger solutions which tend to give a too deep tint for ordinary projection.

The depth of the tint increases with the time of immersion within certain limits. With solutions of the strength given, prolonged immersion after 3 to 5 minutes has very little eflect.

The time of rinsing is an important factor. Using the solutions given, one or two minutes washing is necessary for weak tints, while for stronger tints a mere quick rins-' ing is all that should be given. While the practice is not usually to be recommended, be dispensed The nature of the final tint is independent of the concentration of the otassium ferrocyanid solutionprovided tiie film be immersed for a sufiicient length of time,the maximum eflect with a 1% solution being usually produced within five minutes. A. shorter immersion will, of course, give lighter tints, although this way of modifying the tint is not as desirable as the varying of the time of rinsing. It tends to cause intensification o f tinting during subsequent washing.

The temperature of the baths has a contime of immersion being necessary in the ferric-alum at high in a 1% first example.

i v nitrate,

' The film is immersed in a 1% temperature. Too high temperatures, however, tend to produce reticulation or puckering of the gelatin-, and a temperature of Second ewample-orange tintsolution of uranium nitrate, rinsed and then immersed solution of potassium ferrocyanid'. in the same man$er as outlined above in the. he factors which afiect the tinting aresimilar to those described inconnection with the blue tinting and need not be repeated. An orange tint due to colloidal uranium ferrocyanid is obtained.

It may be noted that the first and second tinting methods may be 'to a certain extent combined to produce darker tints, a small amount of ferricalum being added to the uranium nitrate bath.

T hird emamplcsufid tint.

The film is immersed for a suitable time, say two minutes, in a 1% solution of-lead rinsed, and then immersed in a 5% solution of sodium sulfid for a suitable time, which may be about two minutes. To avoid softeningof the film with these particular solutions, the temperature should not exceed F. A tint due to colloidal lead sulfid is obtained.

Other nitrates, such, for instance, as

eupric nitrate and bismuth nitrate may be substituted for the lead nitrate in this method. The factors of control in this method are the same as those of the previous examples.

It is important that the baths should not quickly deteriorate, and I-have experimentally found that the baths recommended possess long life and are insensitive to light.

Folding tests have indicated that the wear- I .ing qualities of the film are not affected by this method of tinting. Exposure to light by the usual tests has also shown that the tints do not materially alter within periods of time corresponding to the commercial life' of the film. i The iron and uranium ferrocyanids, which are formed in the first and second examples given above, alkali carbonate, caustic. alkali, etc. This is a valuable feature as it enables the operator to remove the tint wholly or partially should he find the color unadapted to the particular subject portrayed by the film. Furthermore, he may tint the film for one exhibit and decolorize it for another exhibit where different lighting conditions prevail. Since the silver image is not materially altered by the above solution it will not be dissolved or altered when the tinting salts are dissolved out, It will be noted from these examples that I carry out mytinting process independently of any light action, making slow printing operations unnecessary.

The tint is quite uniformly distributed throughout the gelatin. Consequently my method may be used not only to tint an even layer of gelatin but may be used to tint gelatin layers of varying thickness such as are produced by printing bichromated gelatin under a negative and dissolving away the soluble gelatin in the well known way to form a gelatin relief image. A monochrom image of desired tint canthus be obtained. The theory of the method seems to be that colloidal substances, such as gelatin, have an enormous number of minute or capillary passages therein into which difiuses' the first solution, which contains the ions of that metal which is to enter into theprecipitated colored particles constituting the tint. Rinsin removes such solution from the surface of the gelatin and, if prolonged diminlshes the concentration of the metallic ions in some or all of the passages of the gelatin. When the gelatinis next placed in the second or precipitating solution containing the anions which are to enter into the precipitate, said solution diffuses through the passages in the gelatin and the anions combine with the metallic ions. The result is a precipitate of colored particles wherever the two ions meet and, due to the minute passages n which they are formed and to the so called protectiveaction of the colloidal gelatin, these parare soluble in alkali, such as net/ are ticles cannot agglomerate but remain dis persed in a finely divided or colloidal state.

' The individual particles cannot be seen by the naked eye or under a low power magnifier, the tint appearing homogeneous. Washing removes the soluble salts which remain after the precipitate is formed and it may also check overtinting. While this is the theory of, the action as now understood, a knowledge of the true theory is, of course,

not indispensable in practising my invention. I

It will be seen from the examples herein above iven that my'tinting process is particular y applicable to colloidal layershaw ing a definite image already formed therein. The colloid is still transparent or light transmitting after tinting, but the light which can pass through it will, of course, be colored. This is particularly important in projection work. Thus with the ferric ferro cyanid blue tint, bluish light will be transmitted, and if the incident light'is white,

certain wave lengths or components thereof will be absorbed or modified by the colored articles in the tint, so that only the wave engths or components corresponding to the blue color will pass through.

ll claim: 1. The process of tinting independently of light action a gelatin layer containing a silver image, which consists in; precipitating suficient colored inorganic salts in dispersed and finely-divided condition in said gelatin independently of said image to permit a substantially full transmission of light waves producing the desired tint but substantially of other light waves.

2. A process of treating independently of light action atransparent colloid containing an opaque image, which consists (if difiusing therein a soluble salt of a metal'oapable of entering into a colored inorganic precipitate and difiusing through said 001-" loid a solution of a compound capable of furnishing a component of said colored precipitate, the salt and compound reacting in the colloid independently of said image to produce dispersed and finely divided col= ored inorganic insoluble particles producing a substantially transparent tint.

3.. The process of tinting independently I of light action a gelatin layer containing an opaque image which consists in treating the same in a solution or a soluble salt of a metal capable of entering into a "colored insoluble compound, rinsing said gelatin and treating said gelatin in a bath of a soluble inorganic reagent which reacts to form a colored insoluble compound of said metal,

whereby a colored inorganic salt is produced in the gelatin independently of said image in finely divided and dispersed condition.

preventing the transmission precipitate, thereby difi'using 4 The process of tinting a body of a transparent colloid which consists 1n diffusing in said body a solution of ferricalum and subsequently diflusing therein a solution of potassium ferrocyanid to produce a chemical reaction within the body and form dispersed and finely divided particles of ferric ferrocyanid giving a blue substantially transparent tint by transmitted light.

5. The process of treatinggelatin contain a ing a photographic image, which consists intreating the same in a ferric alum solution, rinsingthe same, treating the same in a solut10n of potasslum ferrocyanid 'until a tint 3 is obtained, and washing the same to eliminate the remaining soluble compounds,

whereby a substantially transparent tint is, produced. Y Y

6. The process of vtreating photographicgelatin, which consists in treat1n the same in a solution of ferric-alum, rlnsing the same, treating the same in a solutionof potassium 'ferrocyanid until colloidal particles forming a tint are produced, washing the same, and finally controlling the color efi'ect by treating the tinted gelatin in a bath containing a solvent of the particles of the tint.

7. The process of tinting gelatin containing an image, whichconsists in treating the same in a diluted solution of ferric-alum, rlnsmg the same, treating the same in a dilut'ed solution of potassium ferrocyanid unt1l atint is obtained, washing the same,

said gelatin, and washing the gelatin to remove the soluble. salts remaining after the production of thecolloidal precipitate, said to leave the image of the photograph substantiailly unaltered.

9. The process of coloring gelatin associated with the image of I a photograph, which comprises treating said gelatin in a bath containing a soluble salt of a metal ltd ' treatments being composed and controlled capable of entering into a colored colloidal the ions of the metal through said gelatin, rinsing the excess of said solution from the surface of the gelatin, treatingsaid gelatinin abath, containing negative ions capable of: uniting with said metallic ions to form colored in soluble inorganic compounds, until said negative ions diifuse through said gelatin and combine with the diflused metallic ions to form a colloidal colored precipitate appearing as a homogeneous tint to the naked eye, and finally Washing out the 'soluble salts remaining after the formation of the gelatin layer thereon containing a silver image, and inorganic colored salts in finely divided condition dispersed evenly in said gelatin to produce a substantially transparent tint. M

duce' a tint,

Q 11.: As an article ofmanufacture, a light transmitting colloid having an image there-' in, and also having therein finely divided and dispersed inorganic colored salts to pro- I 12; As an article of manufacture, a mo tion picture positive film' -comprising a) transparent flexible base, a layer of transparent gelatin thereon containing a photographic opaque image and colored inorganic salts as a substantially transparent tint in colloidal conditio di t ib in said gelatin. 7

JOHN i. ORABTREE. "Witnesses: v y

W. F; MAN-HOLD; R. L. Srmonrmm. 

